Magnetic separator having two rotating magnetic drums of opposite polarity

ABSTRACT

A magnetic separator having two rotating magnetic drums of opposite polarity which form between them a working air-gap, and having directionally magnetized block magnets on each side of both end-faces of the magnetic drums in a closed magnetic circuit, the magnets being connected together on one side of their poles, in pairs with unlike poles, by means of soft-iron parts, and being provided, on the other side, with pole shoes in which are mounted soft-iron parts designed as axes, the drums each being arranged in a housing comprising slide plates which are located in the working air-gap and which converge at the inlet and diverge at the outlet, the said drums comprising axial grooves distributed radially around their peripheries, or having peripheries of star-shaped cross section.

The present invention relates to a magnetic separator having tworotating magnetic drums of opposite polarity, forming between them aworking air-gap.

Magnetic-drum separators for separating fine and very fine particles,especially weakly mangetizable particles, from bulk material of allkinds, are known (German Pat. No. 943 761). Separators of this kindhave, within each drum, stationary magnets forming, by means of a commonyoke outside the drums, a magnetic system common to both drums, thefield of force thereof extending across the gap between the drums. Insystems of this kind, not only are there large scatter losses at theworking air-gaps, but also uncontrolled scatter, outside the effectivearea, from the working gaps to other components. The result of this isthat the separated material closes the gaps and cause shutdowns, unlesscleaning is carried out regularly.

It is the purpose of the invention to obtain better efficiency bykeeping the external scatter fields as small as possible and by avoidingas far as possible, any scatter outside the effective area.

According to the invention, and in the case of a magnetic separator ofthe type mentioned at the beginning hereof, it is proposed to achievethis purpose in that, arranged on each side of the end faces of themagnetic drums, in a closed magnetic circuit, are two directionallymagnetized block magnets which are connected together, on one side oftheir poles, in pairs with unlike poles, by means of soft-iron parts,and which are provided, on the other side, with pole shoes in which aremounted soft-iron parts, designed as axes, each of the said drums beingarranged in a housing comprising sliding plates which are located in theworking air-gap and which converge at the inlet and diverge at theoutlet, the said drums having axial grooves distributed radially aroundtheir peripheries, or having peripheries of star-shaped cross section.

The result of this is a closed system which has substantially lessscatter than known arrangements, which largely eliminates externalscatter, and which provides a more intense magnetic field in the workingair-gap.

The slide plates preferrably form parts of the drum housing. It isdesirable to design the soft-iron parts in the interior of the drums insuch a manner that they are of segmental or cylindrical cross section,and to arrange them upon an axis.

The object of the invention is explained hereinafter in greater detail,in conjunction with the examples of the embodiment illustrated in thedrawing, wherein:

FIG. 1 is a diagrammatic representation, in part section, of themagnetic separator without its housing;

FIG. 2 is a section through the magnetic separator with its housing,along the line II--II in FIG. 1;

FIG. 3 is a section through the magnetic separator with its housing,along the line II--II in FIG. 1, but with drums and axes of rotation ofa different design, and

FIG. 4 is a section through the magnetic separator, with its housing,along the line II--II in FIG. 1, with a further modification of thedesign of the drums and axes.

According to FIG. 1, the magnetic separator consists of two magneticiron drums 1, 2 and a magnetic system consisting of block magnets 3,4and 5,6 arranged on each side of the end-faces of magnetic drums 1,2 thesaid magnets being connected together, on one side of their poles, inpairs with unlike magnet poles, by means of soft-iron parts 7,8 andcomprising pole shoes 9, 10 and 11, 12 on the other side of the poles.Mounted in the ball-bearings 15 in pole shoes 9,10 and 11,12 aresoft-iron parts designed as axes 13 and 14 for rotating magnetic drums 1and 2. Soft-iron parts 7 and 8 on the one hand, and pole shoes 9,10 and11,12 and axes 13 and 14, on the other hand, provide an absolutelyclosed circuit for the magnetic flux of block magnets 3,4 and 5,6, theeffective magnetic field, and working air-gap 16, being located in thegap between magnetic drums 1 and 2.

Magnetic drums 1 and 2 are arranged respectively in housings 17 and 18.Located in working air-gap 16 of housings 17 and 18 are slide plates19,20 which together form a converging inlet and a diverging outlet oneach side of drums 1 and 2 which they partly surround.

Magnetic drums 1 and 2 have axial grooves 21 distributed radially aroundtheir peripheries and filled with non-magnetic material; or as shown inFIG. 3 they may be of star-shaped cross section.

Edges 22 (FIG. 2), thus formed, provide an intensified magnetic emissionwhich considerably improves the separating action in working air-gap 16,formed by slide plates 19 and 20, through which the material to beseparated pass from top to bottom. In order to increase still furtherthe magnetic flux in working air-gap 16, axes 13 and 14 are of segmentalor cylindrical cross section over the length of magnetic drums 1 and 2.

I claim:
 1. A magnetic separator comprising the combination of tworotatable magnetic drums of opposite polarity forming a working air-gaptherebetween, each said drum including a plurality of groovesdistributed in a radial direction around their peripheries and extendingin an axial direction, said combination further including twodirectionally magnetized block magnets arranged on each side of saidmagnetic drums, said drums being arranged in a housing comprising a pairof slide plates positioned in the working air-gap, said platesconverging at the inlet and diverging at the outlet, said block magnetsbeing disposed in a closed magnetic circuit and being connected in pairsat the bottom part of their poles of unlike polarity by means ofsoft-iron parts, said block magnets having on the upper side of theirpoles of unlike polarity a pair of axially spaced apart pole shoes inwhich soft-iron parts are disposed and which last mentioned soft-ironparts serve as the axles for said rotatable magnetic drums.